Project Summary Recent data suggest ongoing increases in life expectancy are accompanied by widening socioeconomic differences in life expectancy and disability. The overarching aim of this application is to understand the role of socioeconomic factors in shaping ageing outcomes, the innovation lies in the use of multi-state models (MSM) to study multiple health events that occur over the course of aging. Much of the research on aging uses time-to-event or survival analysis, where only one health outcome (chronic disease, multimorbidity, disability, or death) can be examined at a time and the inter-relationships among these outcomes are not considered. We propose to use MSM to examine the role of socioeconomic factors in transitions from a healthy state to chronic disease, to subsequent multimorbidity, to disability and death in a single analytic framework using 30-years follow-up in the Whitehall study. We identify multimorbidity due to aging of populations and poor understanding of their impact on functional impairment, disability and death critical to understanding social disparities in health at older ages. The cross-sectional nature of much of the research on multimorbidity and disability does not allow identification of prevention targets that could be used to close the gap in health status of older adults. Our approach focuses on transitions or changes in health states with ageing and examines the role of socioeconomic factors and how psychosocial, behavioral, and biological factors explain social disparities in these transitions. Our proposal is based on the Whitehall study which has pioneered research on health inequalities. We propose to examine socioeconomic disparities and underlying mechanisms in chronic diseases, transitions to multimorbidity and mortality (AIM 1), examine whether socioeconomic factors buffer the association of multimorbidity with disability, and that of disability with mortality and identify underlying mechanisms (AIM 2), and assess the role of SES in shaping the association of functional impairment (subjective and objective assessments) with mortality, and its role in terminal decline, i.e. accelerated decline in function prior to death (AIM 3). Increased life expectancy and reduced disability rates in the high socioeconomic groups suggest that it is possible to improve aging outcomes in the entire population to ensure that most older adults remain healthy, active, and independent for as long as possible. In order to do this, better understanding is needed of the pathways through which high SES promotes health and functioning at older ages; evidence that this proposal aims to generate.